1. Field of the Invention
The present invention is directed to a hydrodynamic torque converter having a pump wheel and a turbine wheel, the blades of which are held at a distance from one another by an outer torus, wherein a lockup clutch with a piston rotationally connects the turbine wheel to a housing of the converter.
2. Description of the Related Art
U.S. Pat. No. 4,240,532 discloses a hydrodynamic torque converter with a converter circuit having a pump wheel and a turbine wheel, wherein each of these wheel has a blade arrangement to form flow chambers, these blades being interconnected on the outer side and on the inner side by means of a stiffener. Together, the outer stiffeners form an outer torus and the inner stiffeners together form an inner torus. Tongues are fastened in the radial outer region to the outer torus which, like the inner torus, holds the turbine blades at a predetermined angular distance from one another. These tongues serve as control elements for an energy accumulator of a torsional vibration damper of a lockup clutch, wherein the energy accumulator is supported in the circumferential direction by its counter-side at a holder which is fixedly connected with the piston of the lockup clutch. The piston is mounted on the hub of the turbine wheel and is rotationally connected, via the torsional vibration damper, with the turbine wheel which is in turn operatively connected, via the hub, with a driven shaft serving as a driven element. When the piston is brought into contact with a converter housing, a rotational connection can be produced from the converter housing to the piston, and therefore to the driven shaft, via a friction zone having a friction facing.
While there is nothing objectionable about the functioning of a torque converter of the kind mentioned above, the rotational connection between the lockup clutch and the turbine wheel represents a relatively complicated arrangement due to the plurality of tongues. In addition, when the tongues are welded to the outer torus of the turbine wheel, an uneven heating is brought about by the welding process and deformation stresses can accordingly be introduced in the outer region of the turbine wheel. This results in undesirable imbalances at the turbine wheel.